The present invention relates to the cutting up by shearing of elements used in the construction of a nuclear installation. It more particularly relates to the cutting up of melting pots.
The dismantling of nuclear installations is a particular problem worrying the authorities responsible for safety and nuclear protection, as well as nuclear plant operators. For several decades, numerous dismantling means have been developed and experience has shown that it is necessary to improve existing dismantling equipment or create new equipment for this purpose. Numerous countries have started up research and development programs in this connection.
As nuclear installations are of different sizes and types, it is necessary to have a considerable variety of means in order to carry out the dismantling operations. They are generally carried out by cutting up using one of the numerous existing processes, i.e. thermal, electrothermal, pyrotechnic, mechanical, etc.
The choice of a particular cutting up process is a function of numerous criteria, namely the efficiency of cutting up, its cost, use constraints, the pollution level emitted and the material to be cut up.
It is known to carry out mechanical cutting up by using a circular saw, reciprocating saw, disk, abrasive cable and wheel and boring cutting tools. The weight and overall dimensions of these tools make them difficult to remotely handle.
Certain constituents of nuclear installations are particularly difficult to cut up. This may be due to the nature of the material forming them, their thickness and their state. This is particularly the case with melting pots made from alloys of nickel, chromium and iron, such as Inconel 601.sup.(R), which have a thickness of about 10 mm. In addition, spent melting pots have a residual glass deposit on their inner wall, which increases cutting difficulties. As a result it is at present virtually impossible to cut up these pots. Reciprocating saw tests have revealed that roughly two months are needed to cut up such a pot.